package com.itheima.Jiuye02;

public class Bjiben {
    public static void poweron(){
        System.out.println("打开笔记本");
    }
    public static void poweroff(){
        System.out.println("关闭笔记本");
    }
    public static void useDevice(USB u){
        u.open();
        u.close();
        if (u instanceof Shubiao){
            Shubiao sb =(Shubiao) u;
            sb.show();
        }
    }
}
